Electric lamp



ELECTRIC LAMP Filed Oct. 30, 195

3 Sheets-Sheet 1 ROLAND Ly BIENVENUE DWIGHT J. DWENELL SAMUEL E. SWASEY1N VEN TORS FIG.7 W

ATTORN EY PRIOR ART Dec. 18, 1962 s. E. SWASEY ETAL 3, ,5 3

ELECTRIC LAMP 5 Sheets-Sheet 2 Filed Oct. 50, 1959 FIG. H

ROLAND L.BIENVENU E DWIGHT J. DWINELL SAMUEL E.SWASEY INVENTORS ATTORNEV Dec. 18, 1962 s. E. SWASEY ETAL ELECTRIC LAMP 3 Sheets-Sheet 3 FiledOct. 50, 1959 ROLAND L. BIENVENUE DWIGHT J. DWlNELL SAMUEL E. SWASEYINVENTORS ATTORNEY tice 3,069,583 ELECTRIC LAMP Samuel E. wasey,Marhlehead, Roland L. Bienvenue,

Lawrence, and Dwight .l. Dwinell, Reading, Mass assignors to SylvaniaElectric Products Inc, a corporation of Delaware Filed Oct. 30, 1959,Ser. No. 849,869 3 Claims. (Cl. 313317) This invention relates to themanufacture of electric lamps and more particularly to the manufactureof miniature incandescent lamps, i.e,, incandescent lamps which are verysmall in size.

In the manufacture of many types of incandescent lamps, such as thosenormally used for domestic lighting purposes for example, the lampfilament is usually connected, electrically and mechanically, to theinner ends of a pair of lead-in wires which are supported by and extendthrough the press portion of a glass flare which is sealed to the openend of the lamp envelope to provide a closed container. In this type ofconstruction, accurate orientation of the lamp filament within the lampenvelope presents no great problem because the inner ends of the lead-inwires on which the filament is mounted are not apt to be accidentallydisplaced from their desired locus during subsequent lamp manufacturingoperations.

On the other hand, in the manufacture of miniature incandescent lamps,such as telephone switchboard lamps for example, the lamps are so smallthat very serious practical manufacturing difficulties have made itimpractical to utilize the flare type of construction with automaticlamp manufacturing equipment. One of these difficulties, for example, isthe proper initial positioning of the lead-in wires in spacedrelationship within the flare by automatic feeding means, such as shownin US. Patent 2,637,144 to Gardner et al. for example. The smaller theinside diameter of the throat of the flare gets, the greater the problemof properly feeding and orienting the lead-in wires becomes. Heretoforethis problem has been avoided by using other types of mount structures.However, these other types of mount structures, particularly those usedwith telephone switchboard type of lamps, have always been characterizedby certain recognized deficiencies and manufacturing problems as will bedescribed more fully below.

In view of the foregoing, one of the principal objects of this inventionis to provide a high quality mount structure for miniature incandescentlamps.

Another object is to provide a stem structure for miniature incandescentlamps which lends itself to manufacture on high speed automaticequipment.

A further object is to provide miniature incandescent lamps with a mountstructure reproducible with a high degree of accuracy and uniformity oflocation within the lamp envelope.

These and other objects, advantages and features are obtained, inaccordance with the principles of this invention, by providing miniatureincandescent lamps with a stem type mount structure in which the stempress is preferably shaped so that substantially more glass is locatedon one side of the lead-in wires sealed therein than on the other, thusproviding substantially more readily useable material for the insertionof filament support wires. The outside diameter of the neck of the bulband the diameter of the flare of the stem type mount is maintainedsubstantially equal so that in effecting the sealing of these twomembers to one another the bulb is positioned over the mount with theneck of the bulb resting on the adjacent face of the flare adjacent tothe peripheral edge thereof. This is a substantial departure fromconventional techniques normally used in incandescent lamp sealingoperations where stem type mounts are employed. It has the very decidedadvantage that it contributes substantially to the attainment ofuniformly and accurately positioned mounts sealed in their lampenvelopes. It also provides a much more uniformly shaped envelope end towhich a base is affixed, and thus makes possible a substantialimprovement in basing quality.

In the accompanying drawings,

FIGURE 1 is a perspective view of a telephone switchboard type of lampillustrating the conventional construction thereof.

FIGURES 2-18 are details illustrating the parts used and the workperformed thereon in the manufacture of a miniature incandescent lamp inaccordance with the principles of the invention.

FIGURE 2 is a detail of a flare.

FIGURE 3 is a detail of a flare and lead-in wire assembly.

FIGURE 4 is a detail of a flare, exhaust tube and lead-in wire assembly.

FIGURES 5 and 6 are elevational views, taken degrees apart, of theforegoing assembly after formation of the stem press.

FIGURE 7 is a transverse sectional view taken through the stem press ofFIGURE 6.

FIGURE 8 is an elevational detail showing filament support wiresinserted in the stem press.

FIGURE 9 is a transverse sectional view taken through the stem press ofFIGURE 8 showing the disposition of the lead-in wires therein.

FIGURE 10 is an elevational view showing the positions to which thelead-in wire and the filament support wires are deflected to facilitateseverance of the bight of the lead-in wire to form two lead-in wires asshown in FIGURE 11 and the spreading and flattening of the lead-in wiresas shown in FIGURE 12.

FIGURE 13 is an elevational view showing the flattened lead-in Wiresreturned to their normal position before the bight was severed andflattening was effected.

FIGURE 14 is a front elevational view showing the work after hooks havebeen formed at the ends of the lead-in wires.

FIGURE 15 is an elevational view showing some of the filament supportWires deflected clockwise slightly and the lead-in wires deflectedcounter-clockwise slightly.

FIGURE 16 is an elevational view showing the re maining filament supportwire bent counter-clockwise.

FIGURE 17 is an elevational view showing all three filament supportwires and the lead-in wires disposed in their final positionspreparatory to filament mounting.

FIGURE 18 is an enlarged fragmentary detail of the completed stem typemount structure showing the lamp filament attached at its ends to thehooked ends of the lead-in wires and extending through the loops formedat the free ends of the filament support wires.

FIGURE 19 is a perspective view of a completed lamp.

A conventional, commercial telephone switchboard type of miniatureincandescent lamp is illustrated in FIG- URE 1. The first step in themanufacture of this lamp is to start with a piece of tubing 1, form anoutwardly extending peripheral flange 3 on one end thereof and theninsert, radially, into said flange 3 on or more filament support wires5, the number of support wires 5 varying with the type and final shapeof the filament to be used. Formation of the flange 3 and inserting ofthe filament support wires 5 are usually effected on automatic machinerywell known to those skilled in the art. Several of the succeedingoperations, however, are performed manually and require highly skilledand experienced operators to insure some degree of uniformity andaccuracy of workmanship.

An operator, working with suitable tools, bends the filament supportwires to their proper positions and puddles in the lead-in wires 7 intothe flange 3. This operation requires considerable skill because thelead-in wires '7 must be aflixed to the flange 3 at rather criticallocations with respect to one another and with respect to the filamentsupport wires 5. The length of the leadin wires 7 extending above theflange 3 is also critical. The operator then mounts a filament 9 byattaching one end thereof to an end of one of the lead-in wires '7,threading it through loops provided therefor on the ends of the filamentsupport wires 5 and then attaching the other end thereof to an end ofthe other lead-in Wire 7. Since the filament is of accurate pre-determined length held within very close tolerances, it is apparentwhy the relative location of the lead-in wires and filament supportwires are critical as just noted.

A lamp envelope 11 is now slipped over this structure and sealed to thetubing 1 to provide an hermetically sealed device. The envelope 11 mustbe large enough in diameter to clear the mount structure as it isslipped thereover and yet this clearance cannot be a very substantialone because it would tend to increase the already diflicult task ofsealing the envelope 11 to the tubing l with out accidentaliy causing asealing of or abnormal constriction in the tubing itself. After sealingof the envelope 11 to the tubing 1 the device is evacuated through thetubing and finally the tubing is tipped off.

The manner in which the electrical lamp of this invention is fabricatedwill now be described. The first sequence of steps constitutes thefeeding of several individual work components which are then fabricatedinto a single unit. This is done on a suitable lamp stern fabricatingmachine which may be of the type shown in the Gardner et a1. Patent2,637,144 for example. The lamp stem fabricating machine is providedwith a plurality of heads which include work-supporting members forretaining the several work components in predetermined relativepositions. In the operation of the machine, the heads are moved througha path along which certain devices are disposed for operation on thework components to accomplish the desired work fabrication.

At the start, the flare 2 of FIGURE 2, the wire 4- of FIGURE 3 and theexhaust tube 6 of FIGURE 4 are fed sequentially to a machine head andsupported therein in the relative position shown in FIGURE 4. The flare2 and the exhaust tube 6 may be fed by means such as those in theGardner et al. Patent 2,637,144. The wire 4 may be fed in accordancewith the method taught in the Ward Patent 2,762,110 by the means shownand described in the co-pending application of Swasey et a1. Serial No.757,993. With the work components disposed as shown in FIGURE 4, theassembly is heated at several work stations and finally the stem pressis formed in the flare 2 by the action of a pair of dies which move intoencompassing relationship with respect to the molten glass. The shape ofthese dies and the manner in which they engage the molten glass isdesigned to provide a stem press or pinch 8 substantially as shown inFIGURE 7, i.e., a stem press in which there is a substantially largerbody of glass on one side of the legs of the wire 4 sealed therethroughthan on the other. As is shown in FIGURE 6, an exhaust port 10 is formedin the flare 2 adjacent to the stem press 8 while the glass is moltenand at about the same time that the stem press is formed.

Filament support wires are now inserted into the stern press 8substantially as shown in FIGURE 8 by suitable means well known in theart of lamp manufacturing and heretofore employed to insert filamentsupport wires in an arbor but-ton. One, two or several of these supportwires may be inserted depending on the needs of the particular lamp typebeing manufactured. In this case there are three filament support wires,12, 14 and 16 as shown in FIGURE 9, wires 12 and 14 lying insubstantially the same horizontal plane as shown in FIGURE 8.

d It will be noted, as shown in FIGURE 9, that the filament supportwires 12, 14 and 16 are embedded in the side of the stem press 8 havingthe larger body of glass and are insulated from one another within thepress.

To facilitate execution of certain subsequent operations, the wire 4 andthe filament support wires 12, 14 and 16 are displaced by suitable toolsfrom the positions thereof shown in FIGURE 8 to the positions thereofshown in FIGURE 10. With the wire 4 so disposed, the bight 1.8 thereof,shown in phantom in FIGURE 11, is severed to provide two lead-in wires4a and 4b and the new free ends are spread apart slightly and thenflattened as shown in FIGURE 12 to provide flats 4c and dd. The lead-inwires 4a and 4b are then bent back to the position shown in FIGURE 13and hooks 4e and 4] are formed in the flats 4c and 4d as shown in FIGURE14.

The structure is now ready for the final positioning of the lead-inwires and the filament support wires in preparation for the mounting ofa lamp filament thereon. The lead-in wires 4a and 4b are deflected asshown in FIG URE 15, the filament support wires 12 and 14 are bent tothe position shown in FIGURE 16 and the filament support Wire 16 is bentto the position shown in FIGURE 17. A filament 26' is then mounted onthis supporting structure, the filament being threaded through filamentretainers, as loops, provided therefor on the free ends of the filamentsupport wires 12, 14 and 16 and the ends of the filament being clampedin the hooks 4e and 4] on the lead-in-wires 4a and 4b.

The mount assembly of FIGURE 18 is then sealed in a lamp envelope andthe sealed envelope is evacuated and finally tipped oflf to provide thelamp shown in FIGURE 19. As was mentioned above, and as will be notedfrom an examination of FIGURE 19, the neck of the bulb 22 is sealed tothe adjacent face of the flare adjacent to the peripheral edge thereof.This avoids the variations and dislocations of the disposition of themount structure during sealing which occur many times with some of thewellknown sealing techniques.

What we claim is:

1. An incandescent electric lamp comprising: a lamp envelope; are-entrant stem disposed within and hermetically sealed to said lampenvelope, said stem having a stem press formed therein and an exhausttube depending therefrom; a pair of lead-in wires sealed in said pressintermediate the ends thereof, said lead-in wires extending through saidpress and being offset from the major transverse axis thereof; at leastone filament support wire having one end thereof embedded in said presson the side thereof opposite said lead-in wires, the other end of saidfilament support wire being provided with a filament retainer; and afilament supported by said lead-in wires and said filament support wire,said filament being supported by said retainer of said filament supportwire and being attached at its ends to the adjacent ends of said pair oflead-in wires.

2. An incandescent electric lamp comprising: a lamp bulb having asubstantially cylindrical neck portion; a stern, having a press formedin one end thereof and a flare formed in the other end thereof, disposedwithin said bulb, the neck of said bulb being sealed to said flareadjacent to the peripheral edge thereof; a pair of lead-in wires sealedin said press intermediate the ends thereof, said lead-in wiresextending through said press and being offset from the major transverseaxis thereof; at least one filament support wire having one end thereofembedded in said press on the side thereof opposite said lead-in wires,the other end of said filament support wire being provided with a loop;and a filament supported by said lead-in wires and said filament supportwire, said filament extending through said loop of said filament supportwire and being attached at its ends to the adjacent ends of said pair oflead-in wires.

3. The combination of claim 2 in which the outside diameter of the neckof the bulb and the diameter of the flare are substantially equal.

References Cited in the file of this patent UNITED STATES PATENTS 6Laskey Nov. 8, 1927 Anderson et al. Feb. 7, 1939 Cartun et al. June 27,1939 Fantur Aug. 17, 1943 Flaws Oct. 31, 1944 Acheson June 15, 1948 ChunDec. 13, 1949 Wiedenmann Nov. 24, 1959

